Ravi Kant (top) at the project site; a man (above) hammers at the wall. Telegraph pictures

Singur, June 27: Tata Motors managing director Ravi Kant reviewed the progress of the Nano plant inside as Trinamul Congress supporters pulled down a portion of its boundary wall around 5km away.

A larger-than-usual police presence near the entrance for VIP visitors today had apparently led to lax security towards the rear and the Trinamul activists took advantage of it.

A procession sneaked in through a gap in the wall and as it proceeded towards the main plant, where Kant was doing the rounds, the dozen-odd policemen and Rapid Action Force jawans posted there became alert.

As the police tried to shoo the group away, a mob armed with sledgehammers, crowbars and beer bottles started hammering at the wall half a kilometre away.

Heavily outnumbered, the police team ran to thwart the demolition of the wall and encountered bricks and broken bottles.

Reinforcements arrived and lathicharged the intruders. A dozen tear gas shells were also lobbed and the villagers fled towards Khasherbheri, Manasatala and neighbouring areas.

“Our leaders had told us that top Tata Motors officials would visit the plant today and a large-scale agitation should be launched,” said Mahim Barui, 24, a farm labourer.

After a phone call to Mamata Banerjee in Calcutta, the local Trinamul MLA asked supporters to block Durgapur Expressway and Delhi Road to prevent Ravi Kant from returning to Calcutta.

A few hundred people armed with sticks and tree branches sat on the roads for an hour and a half from 3pm. They did not know that Kant had left for the city through the Kalyani Expressway around 4pm, making a 39km detour.

“Ravi Kant was here to understand the progress of the plant and the vendor park,” said a Tata spokesperson.

Girish Wagh, who headed the team that conceived and designed the Nano, took Kant around the plant.

With them were Cyrus P. Mistry, managing director of Shapoorji Pallonji & Co, the developer of the project, M.V. Rao, managing director of the West Bengal Industrial Development Corporation, and its executive director, finance, Subroto Gupta.

Kant, who arrived a little before 10.30am in a convoy of 14 cars, visited each shed and the vendor park.

Industries secretary Sabyasachi Sen joined them for a review meeting. “It was a usual periodic review where issues like drainage were discussed,” said Sen.

Work was stalled for several weeks last monsoon because of flooding at the site.

The level of the land has since been raised.

Kant, who had been sent satellite pictures to give him an idea of the extent of flooding and the steps to be taken, had expressed concern about this monsoon during his first visit to the site in February.

He will meet the chief minister tomorrow.

In February, Kant had said the Nano would hit the market by Durga Puja. He chose not to comment on the rollout today.

Mamata said: “We will not allow the Tatas to roll out cars until the forcibly acquired land is returned.”

Hooghly superintendent of police Rajeev Mishra said three policemen were injured in the clashes. The Trinamul-led Save Farmland Committee said at least 20 supporters were injured.